Condenser leadin for high electric potentials



P. KNIEPEN Aug. 31, 1943.

CONDENSER LEAD-IN FOR HIGH ELECTRIC POTENTIALS Filed June 11, 1941 NVENTQR fieZr-K en ATTORNEY Patented Aug. 31, 1943 CONDENSER LEADIN FOR HIGH ELECTRIC POTENTIALS Peter Kniepen, Berlin, Germany; vested in the Alien Property Custodian Application June 11, 1941, Serial No. 391,525 Germany March 21, 1940 6 Claims. (Cl. 174-9) high vacuum as the dielectric in place of the insulating material.

By choosing a high vacuum as the dielectric, the electric stress or load of an insulating material is obviated. This, on the one hand, leads to a higher breakdown voltage and, on the other hand, to lower dielectric losses and smaller ca pacitance. Moreover, irregularities in the construction of the dielectric in the object of the invention are impossible with the result that the lead-in according to the invention is more reliable.

I have found that in order to obtain the most emcient action in the arrangement according tothe invention, it igexpedient that the outside radius of the current-carrying conductor be at the ratio lte to the inside radius of the grounded metal envelope. e being the base of the natural logarithms. For this ratio and for a given diameter oi the external envelope, there results the lowest field strength on the surface of the inner conductor.

For very high potentials it may be expedient to provide additional equi-potential surfaces between the two conductors. It is expedient that also in this case the stated law should be fulfilled for neighboring equi-potential surfaces, namely, that the radii are at a ratio of l:e.

-An exemplified embodiment of the invention is schematically shown in the appended drawing. In this fi ure, the length has been considerably reduced in respect to the width in order to show more clearly the various parts. In a practical embodiment the total length was about 1 m., while the diameter of the glass or ceramic tube which was used was about 15 cm. In an arrangement of this type, alternating potentials oi more than 300,000 volts could be handled. V

The figure illustrates by way of example a vacuum vessel l consisting of glass or ceramic which in the center or axi comprises the currentcarrying conductor 2 being, for instance, or tubular shape. The tubular conductor 2 is fixedly attached at the seal 3, while at the seal 4 it is provided with a cap 5 located within vessel I. The cap 5 may expand and move over in its position nearer the end seal portion 4 upon the conductor being heated, thereby compensating for the change in length. Current is fed in at the point of cap I by means of a movable conductor which is provided with a loop portion 6. Stated in another way, the passage of the high electric current will cause exp nsion or conductor 2. This expansion is taken up by loop 6. However, as the presence of loop 6 increases the amount of metal in the electrical field at this point, the electrical stress is increased and will give rise to undesirable brushing. Therefore, cap I will function as a shield to reduce the undesired brushing.

In the exemplified embodiment shown, the cylinder 1 takes the place of the normally used grounded external envelope. The said grounded internal cylinder 1 is supported by a stem 8. One end of the support stem 8 is connected to the cylinder I and the other end is connected to an external protective metal cap 8, which may be connected to ground or an equivalent potential. If necessary, a plurality of stems, for instance, three, may be used for additional support of the tubular piece 1 rather than only one stem. The ends of the tubular piece 1 arebent inwardly away from the insulating wall in order to decrease the electric stress of the ends of the wall. Moreover, the ends are greatly curved or rounded. Between conductor 2 and tube 1 is an intermediate tubular part I which is supported by two stems 9 and I0 is arranged to be in capacitive relationship with both the normally. grounded tubular conductor and, as such, divides the potential stress thereon. Attachment to stem 9 is made elastic by a leaf spring II for obtaining yieldingness also at this point to provide for thermal expansion between the support and the intermediate tube. The ends of tube 1' are bent and rounded outward in order to decrease the field stress with respect to conductor 2.

The lead-in according to the invention is attached to a pump and evacuated and outgased in the usual manner known in the art of X-ray tubes and high potential valves. In this connection, it is expedient to impress potentials of 100,000 volts and more upon the electrodes during the last stages of the outgasing. After the tube has been sealed and the pump detached, the extensions or appendages containing phosphor "and llareusedi'orbindingtheremaining gases after cvacuationasknownintheart.

It is understood that of course all metal parts are rounded and polished as known in the art for reducing brushing of high potentials, and that the points of contact between the insulators and the metal are protected in a suitable manner against high potentials acting thereon.

What is claimedis:

1. A vacuum type condenser lead-in bushing comprising a cylindrical enclosing vemel of insulation material, a conductor passing through the axis of said enclosing vessel and sealed to each of the ends thereof, a first cylindrical metallic member surrounding said conductor, supporting means for said first cylindrical metallic member and supported by a seal located at the side wall of said enclosing vessel, a second metallic member located intermediate said conductor and said first cylindrical member and in capacitive relationship therewith, and a pair of insulating supports located at the side wall of said enclosing vessel.

2. A vacuum type condenser lead-in bushing comprising a cylindrical enclosing vessel of insulation material, a conductor passing through the axis of said enclosing vessel and sealed to each of the ends thereof, a metallic cap secured to one end of said conductor and located intermediate the ends of said enclosing vessel, a first cylindrical metallic member surrounding said conductor, supporting means for said first cylindrical metallic member located at the side wall of said enclosing vessel, a second metallic member located intermediate said conductor and said first cylindrical member and in capacitive relationship therewith, and a pair of insulating supports located at the side wall of said enclosing vessel.

3. A vacuum type condenser lead-in bushing comprising a cylindrical enclosing vessel of insulation material, a conductor passing through the axis of said enclosing vessel and sealed to each of the ends thereof, a metallic cap secured to one end of said conductor and located intermediate the ends of said enclosing vessel, said conductor having a loop intermediate said cap, and one of the ends of said enclosing vessel, a first cylindrical metallic member surrounding said conductor, supporting means for said first cylindrical metallic member located at the side wall of said enclosing vessel, :2. second metallic member located intermediate said conductor and said first cylindrical member and in capacitive relationship therewith, and a pair of insulating supports located at the side wall of said enclosing vessel.

aavacuumtype condenserlead-inbushing a cylindrical enclosing vessel of insulation material, a conductor passing through the axis of said enclosing vessel and sealed to each oi the ends thereof, a first cylindrical metallic member surrounding said conductor, supporting means for said first cylindrical metallic member located at the side wall of said enclosing vessel, is second metallic member located intermediate said conductor and said first cylindrical member and in capacitive relationship therewith, a pair of insulating supports located at the side wall of said enclosing vessel, and an elastic link supporting member located intermediate one of said last-mentioned pair of insulating supports and said second metallic member for permitting thermal expansion therebetween.

5. A vacuum type condenser lead-in bushing comprising a cylindrical enclosing vessel of insulation material, a conductor passing through the axis of said enclosing vessel and sealed to each of the ends thereof, a first cylindrical metallic member surrounding said conductor supporting means for said first cylindrical metallic member located at the side wall of said enclosing vessel, said first cylindrical metallic member having both of its ends rounded over inwardly to face said conductor, a second cylindrical metallic member located intermediate said conductor and said first cylindrical member and in capacitive relationship therewith, said second cylindrical member having both of its ends rounded over outwardly away from said conductor and a pair of insulating supports located at the side wall of said enclosing vessel.

6. A vacuum type condenser lead-in bushing comprising a cylindrical enclosing vessel of insulation material, a conductor passing through the axis of said enclosing vessel and sealed to each of the ends thereof, a metallic cap secured to one end of said conductor and located intermediate the ends of said enclosing vessel, a first cylindrical metallic member surrounding said conductor, supporting means for said first cylindrical metallic member located at the side wall of said enclosing vessel, a second metallic member located intermediate said conductor and said first cylindrical member and in capacitive relationship therewith, a pair of insulating supports located at the side wall 01 said enclosing vessel, and a metallic cap located outside said enclosing vessel at the portion of the side wall where the support means for said first mentioned cylindrical metallic member terminates.

PETER KNIEPEN. 

